[Pw_forum] high-symmetry point is wrong in the output of bands.x

[Paolo Giannozzi]

On Thu, Apr 13, 2017 at 3:11 AM, balabi <balabi at qq.com> wrote:

> I am using QE6.1. I found the high symmetry point in the output of bands.x
> is not right.

sure? your system has a FCC lattice (ibrav=2). Find a picture of the
Brillouin Zone and of high-symmetry points, for instance this one:
http://www.iue.tuwien.ac.at/phd/dhar/node18.html
Where do you see that X is (1/2, 1/2, 0) ?

Paolo

> Take copper as an example, set k path as below in bands calcuation
>
> K_POINTS tpiba_b
> 2
> gG 20
> X 1
>
> a possible X coordinate should be "0.5 0.5 0". However, the output of
> bands.x is
>
> high-symmetry point:  0.0000 0.0000 0.0000   x coordinate   0.0000
> high-symmetry point:  0.0000 1.0000 0.0000   x coordinate   1.0000
>
> "0 1 0" is definitely not right for X point.
>
> The reason I want to use high symmetry point information is that I want to
> write an automatic k path transformation tool from PW to wannier90 input win
> file.
>
> below are input files for test
> ---------------------------------------
> copper.scf.in
> ----------------------------------
> &control
>     calculation='scf'
>     restart_mode='from_scratch',
> pseudo_dir = '/mnt/e/DFT_code/QE/pseudo',
>     outdir='./'
>     prefix='cu'
>  /
>  &system
>     ibrav = 2, celldm(1) =6.822, nat= 1, ntyp= 1,
>     ecutwfc = 30.0
>     occupations='smearing', smearing='cold', degauss=0.02
>  /
>  &electrons
>  /
> ATOMIC_SPECIES
>  Cu 63.546 Cu.pz-n-van_ak.UPF
> ATOMIC_POSITIONS
>  Cu 0.0 0.0 0.0
> K_POINTS (automatic)
> 8 8 8 0 0 0
> ----------------------------------------------
> copper.bands.in
> -------------------------------------------
> &control
>     calculation='bands'
>     restart_mode='from_scratch',
> pseudo_dir = '/mnt/e/DFT_code/QE/pseudo',
>     outdir='./'
>     prefix='cu'
>  /
>  &system
>     ibrav = 2, celldm(1) =6.822, nat= 1, ntyp= 1,
>     ecutwfc = 30.0
>     occupations='smearing', smearing='cold', degauss=0.02
>     nbnd=12
>  /
>  &electrons
>  /
> ATOMIC_SPECIES
>  Cu 55.85 Cu.pz-n-van_ak.UPF
> ATOMIC_POSITIONS
>  Cu 0.0 0.0 0.0
> K_POINTS tpiba_b
> 2
> gG 20
> X 1
> ----------------------------------
> bands.x.in
> --------------------------------
> &bands
> outdir='./',
> prefix='cu',
> filband='bands.dat',
> /
>
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-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222